Spectral and energy characteristics of a pulsed hydrogen fluoride laser and rotational relaxation of HF molecules

The spectrotemporal and energy characteristics of the radiation of a pulsed chemical H₂—F₂ laser were calculated on the basis of a multilevel model taking into account the nonequilibrium population of the rotational levels, and were compared with experimental data. The theoretical model took into account the stimulated emission of radiation as a result of the ν, j — 1 → ν – 1,j transitions (ν = 1 – 6 and j = 4– 12) in the HF molecule. The rotational relaxation rate constants of the HF molecule were varied in the calculations. Comparison of the calculated and experimental spectral characteristics of the laser radiation indicates that the rate of the rotational transitions involving high (j = 10 – 12) rotational sublevels of HF is insufficient, leading to an appreciable reduction in the energy of the output radiation for lines with such values of j, compared with lines characterised by j7nbsp;= 7, 8.